Method of making endless belts



w. c. CORYELL. METHOD OF MAKING ENDLESS BELTS.

APPLIC ATION FILED wLv'sflsl'l.

Patented July 8, 1919.

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UNITED STATES PATENT OFFICE.

WILLIAM C. CORYELL, F YOUNGSTOWN, OHIO.

METHOD OF MAKING ENDLESS BELTS.

Specification of Letters Patent. Patented July 8, 1919. 1

Application filed July 6, 1917. Serial No. 178,924.

. belt.

Briefly stated, I produce an endless belt out of a seamless ring of steel or other suitable metal, by expanding the ring by rolling, hammering, or pressing, thereby increasing its length and, reducing its thickness. Generally, the roughing work will be .done while the metal is hot, and the finishing work while the metal is at a lower temperature, or when it is cold. The cold working permits of more exactness in the finished belt and produces a better quality of steel and a better surface. Finally I trim the edges of the belt, preferably in a trimmer, and round oif the edges by grinding or filing, and thus obtain a smooth edge. After grinding, the edges may be more highly finished by polishing. In some instances working stresses. It possesses other advantageous qualities which will appear more fully hereinafter.

The accompanying drawing will assist in following the steps of the process and in illustrating the characteristics of the belt. The scope of the invention will be particularly pointed out in the appended claims.-

In said drawing Figure 1 is a diagrammatic view of a blank metal ring in position between the reducing elements of a reducing machine, such as the rolls of an endless belt mill; Fig. 2 is a similar view showing the ring somewhat enlarged; Fig. 3 is a somewhat similar view illustrating the loop of metal at the conclusion of the hot working operation; Fig. 4 is a view representing the cold rolling operation; Fig.

5 is a sectional view, considerably enlarged,

illustrating the trimmed and rounded edges -of a belt; Fig. 6 is a perspective view of a completed belt; Fig. 7 is a transverse section, on an enlarged scale, of the loop as it appears immediately following the cold rolling operation and illustrating, by dotted lmes, portions that may be cut away by grinding; Figs. 8 and 9 are diagrams illustrating the deformation of the metal as it passes through the rolls; Fig. 8 being a plan view and Fig. 9 a vertical section of the metal in engagement with the rolls. Throughout these views like characters refer to like parts.

Referring to. the drawing in detail, 10 designates the ring of metal from which the finished belt is to be produced. The ring may be produced in various ways. Thus it may consist of a short section of seamless steel pipe Or tube. Again it may consist of a block of metal which is perforated and turned down so as to form a ring. In other instances, it may be a ring punched out of a plate. I prefer the section of a seamless tube, because if the ingot, from which the tube is made, contained blow-holes or segregation, the defects are more certain of being eliminated than when plates, welded tubes, or welded rings are used. The operation of expanding the ring 10 is performed principally by hot rolling, or by hot hammering or pressing between cylindrical surfaces. The ring is first heated and then reduced by the reducing elements of a reducing machine, such as the rolls of an endless belt mill, the hammer and anvil of a hammering machine, or the jaws of a press or squeezing machine. In the present disclosure the ring is shown threaded upon the roll of a belt mill of the kind illustrated in my application Serial No. 59,582, filed November 4, 1915, and patented July 17, 1917, as Patent No. 1233647. The reducing elements are the rolls 11 and 12. As these are operated, the length of the lo0p.10 is increased, its thickness is decreased, and its width is increased very slightly. These three deformations are called, respectively, elongation, reduction and spread, and are expressed numerically in percentage of the original dimension. When the elongation :in my Patent No. 1,221,029,

with roll 12.

33, 1917. In this mill it is tween the rolls 11' and 12' which cooperate This cold rolling gives the.

steel a permanent set, greatly raises its yield point and permits of most exact rolling as to length, thickness and surface finish.

The amount of cold rolling will vary with the metal used. Thus some steel will take upward of twenty-five per cent. elongation between annealings, while other steel will not elongate more than ten per cent. withthe rolls out showing signs of being overworked. The annealing and also the proportion of carbon, nickel and other alloying elements each have their effects.

The effect of overworking the metal in rolling or hammering or squeezing, first ap-' pears at the edges of the band. This is because of the more severe working of the metal at this point than elsewhere across the section. The spread between the rolls is much less inactual displacement than is the reduction in thickness. The elongation is almost exactly inversely proportional to the reduction. The Figs. 8 and 9 exaggerate the spread so as to make the action between the rolls more clearly understood. However, the working of the metal ismore severe at the edges than elsewhere and consequently the edge is the location of the first breaking down of the metal .due to overwork. This action will be apparent from a consideration of the diagrams of Figs. 8 and 9. In these figures the metal is shown passing between 11 and 12. A similar action will occur where hammering or other equivalent reducing means are employed. In these diagrams the longitudinal lines 17 and the transverse lines 18 illustrate respectively the relative lateral and longitudinal displacements of particles of metal before reaching the'rolls, while passingbetween them, and

. after leaving them. From the position of these indicating lines it will be seen that the metal has a slight bulge in breadth and thickness, as indicated at 19 and 20, due to the squeezing of the metal by the rollsas the piece is entering. As these lines clearly show, the piece, while passing between the rolls, gradually decreases in thickness in conformity to the curvature of the rolls, as

indicated by 21, and gradually increases in width.- as indlcatedat 22. It will be seen .that the center or axial line 17 has no distortion. Departing from that line and moving toward the edges, lateral distortion takes place and gradually at the outer edges. Likewise, in moving toward the top and bottom from the axial line 17 vertical distortion begins and increases to 'a maximum at the top and bottom surfaces. faces, however, is less than that at the edges. From these considerations, it is clear that the working of the metal is more severe at the edges of the strip than elsewhere.

Because the edge is more severely worked than the mid-portions of the band, it is des'irable to trim oflf a small portion of the edge, as indicated at 14 in Fig. 7 Trimming has the additional advantage in that it straightens the belt. The trimming may be done in any desired way, as by the use of a trimmer. By the trimming operation, the edges are brought to lie in parallel planes. Any incipient but'invisible cracks are thus removed.

The trimmer does not leave a true and uniform edge, so the belt is putthrough an operation of having the edges rounded. This may be done with abrasive wheels or with files. The edges are thus made smooth and uniform and straight. There is also less danger of the edge cutting any object which it may rub against. However, in good present practice all exposed belts, whatever the material, are protected by inclosures.

The dressing of the edges is an important and necessary step in the manufacture of the belt. It leaves the edges free of the tiny ragged edge or other defects left by the shears. All fractures, even microscopic ones, are to be avoided. Grinding the edges removes these. If left in the belt, the tiniest of fractures would develop into a large one, which in time would ruin the belt. If the abrasive wheel or stone be rough, then I would burnish or polish the edge so as to remove the stone marks. In any event, smoothly polished, rounded edges, lying in parallel planes, arev obtained before the belt is finished.

Besides the steps which have been herein set forth, the belt may have one or both of its surfaces ground off or otherwise dressed, as indicated at 15 of Fig. 7 to give a'desired thickness and configuration to the transverse section of the belt. Furthermore, it may be annealed from time to time. Whether the annealing is done or not will depend largely upon the conditions existing in any partlcular case. In some instances it may be desirable to pickle the ring because of the scale being formed during annealing. Or, after cold rolling, the belt may be pickled so as to cleanse it for a nickel-plating or other metal coating rocess. j The edge of the belt may be dresse several times during the complete course of its manufacture, and the sur increases to a maximum The distortion at-these latter sur- I The belt which I have produced has many advantages over belts of the prior art. Thus it may be used with one pulley, or three pulley belt tighteners, which require short turns and an engagement of one side of the belt at one point and of the other side at another point. The belt which I have produced, because of its high tensile strength, elasticity and permanent non-elongation under high working stresses, can also be used in making a very short drive. It would not be practicable to use leather belts or rope drives in this Way. It has been common practice heretofore, when such short drives were required, to use toothed gearing. Because of the great tensile strength and the unyielding elastic property of my belt, it is also capable of use in vertical drives, that is, in drives where one pulley is directly above the other. Ordinary belting, due to its yielding character, depends upon its weight on the pulley for its adhesion and therefore cannot be used in a vertical drive for it does not rest or lay on the lower pulley. Also my belt has no practical limit of speed since it canv safely run as fast as the bursting speed of the fastest pulley. Then, my belt runs extremely smooth, without jar, vibration or appreciable slip. My belt is not affected expansively by moisture and consequently is independent of wet and dry atmbsphere.

Although I have frequently referred to steel as the metal for producing the belt, I may under certain conditions use phosphor bronze or other alloys of high tensile strength, high yield point and high modulus of elasticity. In general, in'the manufacture of my belt, I prefer a metal having a high yield point or elastic limit, such as rolled or hammered carbonsteel, nickel steel, or other alloy steels. This elastic limit is far beyond that of all present belt materials. For exam lo, I may employ steel having an elastic lim1t of 160,000 pounds or more per square inch of section and an. ultimate strength of 180,000 pounds or more per square inch. The elastic limit of belting in use at present is so low and variable as to-be indeterminate. Consequently it is continually yielding under ordinary working loads. The

. ultimate strength of leather is about 3,000

pounds per square inch of section. With a factor of six for each material, the steel belts may be worked at 30,000 pounds tension er square inch of section, while the leat er may be worked at 500 pounds per square inch of section. Under these conditions, with the modulus of elasticity of steel at 30,000,000 and of leather a 12,400, the steel I will stretch about 0.10 inch per 100 inches of length'and theleather will stretch about 4.0 inches per 100 inches of length. In other ed to a pull of 30,000 pounds per square inch will elongate 1 inch, while leather 2.06 feet I words, a strip of steel 83.0 feet long subjectlong subjected to a' pull of 500 pounds per square inch ofsection will elongate 1 inch. Relatively then, leather, when stressed to one-sixth of its ultimate strength, will stretch about 40.0 times as far as steel when stressed to one-sixth of its ultimate strength. Furthermore, when the loads are removed the steel returns absolutely to its original length, while the leather does.not. The working strength of steel is 60 times greater tion, and. about 4 times greater when'compared per inch of width. Thus my belt is practically freefrom permanent elongation at high working stresses and is truly elastic, returning to its exact original dimension when the load is removed, while a leather belt stretches while in use and is left elongated after use. In other words, leather yields under ordinary working stresses, and steel does not yield at all under severe working stresses.

It should be borne in mind that while some present belt materials have less elongathan that of leather per square inch of section under stress than leather, their ultimate strength is also less, so that in referring to leather as I have done above, I intended to select the most representative belting material.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of making an endless metal belt which consists in gradually expanding a ring of metal of small peripheral length and considerable thickness to a continuous loop of a greatly increased but desired length and greatly reduced thickness, and then dressing the surface and edges of the loop toa desired thickness j and breadth, thereby producing an'endless belt of desired length,

readth and thickness, the dressing of said edges including trimming to remove defec- .tive material.

belt which consists in gradually expanding a ring of metal of small peripheral length and small flexibility to a continuous loop of a greatly increased but desired len h and a greatly increased'fiexibility, and t en trimming the edges, thereby producing a belt of desired length, thickness and wldth, said trimming being for the purpose of' removing defective material.

3. The method of making an endless metal belt which consists in heating a'ring of metal of small peripheral length and considerable thickness, working it while hot to increase its length and to reduce its thickness to nearly that desired, and then rolling it when cold so as to bring it to the exact edges to remove defective material.

4. The method of making an endless metalofl of the edges serving to remove defectivematerial.

5. The method of making an endless metal belt which consists in heating a ring of metal of small peripheral length and 'considerable thickness, working it While hot to increase its length and to reduce its thickness to nearly that desired, then rolling it when cold to bring it to the exact length desired, and then dressing off its edges so as to make them round and smooth, said dressing including the trimming away of defective material.

6. The method of making an endless metal trimming being for the purpose of removing I3 defective material.

In testimony whereof I have hereunto subscribed my name this 5th day of July, A. I). 1917.

WILLIAM G. CORYELL. 

